Process of making cement clinker and apparatus therefor.



O. ELLIS. PROGESS OF MAKING CEMENT GLINKER AND APP LRATUS THEREFOR.

Patented Sept. 14, 1909.

APPLICATION FILED MAY 14, 1906.

Therefor and I one s'r' CARLETON ELLIS, 01? WHITE PLAINS, NEW YORK,AS$I,G NOR, .BY DIRECT AND MESNE ASSIGNMENTS, TO PINE STREET.PATENTSJERSEY.

COMPANY, A CORPORATION OF NEW PROCESS OF MAKING CEMENT CIiINKER ANDAPPARATUS THEREFOR.

Specification of Letters Patent. Patented Sept. 14, 1909. I

Application filed May 14, 1906. Serial .No. 316,740.-

To all whom it may concern."

Be it known that I, CARLETON Euas, a citizen of the United States,residing-in White Plains, county of VVestchester, and State of New York,have invented certain new and useful Improvements in Processes of MakingCement Clinker and Apparatus do hereby declare the following to be afull, clear, and exact description of the same, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to processes of making cement clinker andapparatus therefor; and consists in certain novel means and methods forconverting raw'cement materialsinto finished clinker; all as more fullyhereinafter set forth, matters of. novelty -be-.

ing particularly pointed out in the appended claims.

At present, cement clinker is generally produced in this countrybypassing the .dry, finely powdered rawmaterials down and through a rotaryinclined kiln past a flame burning at or near the mouth thereof andregulated to produce a clinkering heat in its vicinity. Said 'materialsare enerally a mixture of. limestone and argilT Although any form ofcalcium carbonate,

. chemically considered,

should do as Well as limestone, as, for instance, marl, limestone 'isgenerally preferred in making-artificial mixtures of calcium carbonateand argilla'ceou's silicates and-alumina of "the clay,-

laceons silicates such as cementrock since the composition is rarelythat corresponding to the "best cement, correcting additions. of eitherthe. one component or the otherare generally made to rectifysuchcomposition. In the kiln, the reactions occurring arc'many and diverse,but for convenience they may begrouped into two classes; calcining-andclinkering. Clinkering is the operation b \vhich'free lime unites withthe silica, argi aceous- Sillf cates or clay, either artificially ornatu rally produced, as in the cement rock-1" dinarily andsuperficially,

slate, etc, to form the peculiar calcareous compounds whose presenceconfers setting qualities on the finished cement. Galcining is thereaction by which the carbonates of the limestone are freed of theircarbon dioxid, and the lime, magnesia, etc., set free. Clinkeringrequires an enormously high temperature,- approaching 3000 Fahn, butabsorbs little heat, probably even liberating some. This hightemperature is necessary tofrit or soften the argillaceous silicates ofthe clay and slate components and place them incondition for-chemicalunion with the lime. Calcining on the other hand, takes place atcomparatively lowtemperatures but absorbs muchheat, being endothermic.And likealll'endothermic reactions, it is slow, good calcination witheifective utilization of heat requiring a relatively long period oftime, even Where the materials, as is usually the case intcement making,are very finely wdered.

Whatever the origin of the cement materials,-they are invariablyintroduced into the kiln in the form of-a very fine, well mixed powder,frequently so fine as to alloiv per cent. to pass through a lOO meshsieve. This fine-grinding is .for anumber of reasons. On'eis that inthe- -clinkering operation the cement-forming ingredients (that is, thelime and the argillaceoussilicates) must be presented. to each other formutual reaction in the form of uniformly and homogeneously admixed,veryfine powders. Solids as solids do-notreact 0n each'other to anyextent orsintering in the clinkering zone cannotbe allowed to go veryfar without danger to the quality of the clinker. The-reaction ofparticlesof cement materials on each other-is therefore largelysuperficial, and if a par-v ticle of clay or lime, for instance, beadmpar-atively-coarse, it will only be converted leaving a kernel orcore of unconverted'material; this being particularly the case if thecalcination is not complete at the-time of clinkering since calcinationahsorbsheat and therefore prevents interior penetrationof theclinkeringlieat into such a particle. Another reason for the finegrinding,- isthat the cement kiln 'as ordinarily operated calciner,toolittle time being afforded and the contact of-thchot gases-with thccalcintl'ie degr'ee of liquefaction or,

and constructed is not a good usually supposed that it is better toincrease the surface exposure by such fine grinding. This reasoning,however, is not quite correct since the finer the powder undertheconditions in the calcining zone the slower is the penetration ofheat. In the traveling stream of flour-like material in the calciningzone, there is a heat-absorbing liberation of carbon dioxid(calcination) and this compara tively cool heavy gas remains in thestream as a bathing gas layer, retarding the evolutionof more carbondioxid under the ordinary laws of mass action, preventing the access ofthe hot flame gases to the surfaces of the calcinating material andtaking up the communicated heat from such gases.

In the ordinary operation of the ordinary kilns, as a matter of fact,the diverse re quirements of the various operations are not well met,attention being directed mainly to the clinkering and the calcinationbeing allowed, more or less, to take care of itself.

The flame of aerially-suspended fine fuel burning in the mouth of thekiln which is customarily employed, affords the necessary hightemperature for the clinkering and the hot gases coming from it areallowed to do what calcining they will, completion of calcination beingdone in the cl nkering zone proper under the influence ofithe clinkeringflame. Unfortunately, as stated, in such or dinary kiln processes, thetime afforded for calcination is not sufficient nor are other conditionssuitable. In the ordinary operation of the ordinary kiln, of the 35 percent.,

or thereabouts, of carbon dioxid present in the original raw materials,at times a third or quarter remains after the material passes throughthe calcining zone and enters the clinkering zone proper. The result isa sudden chilling at-this point as the silica and argillaceous silicatesbegin to act upon residual unchanged carbonate with expulsion of carbondioxid, with the. production of rings in the kiln, superficially frittedand inwardly unchanged lumps, etc. I

serious trouble is due to the dusting. As

Another stated, the material is very finely owdered and the gas evolvedin thetrave in mass lifts more or less-of it as dust and d elivers ittothe draft .to becarried forward toward the stack. This is one of thereasons why heat regenerators, recuperators andsthelike have never beenpracticable with rotary cement kilns since the evolved dust quicklyclogs them.'-,

By omitting the fine-grinding pf the materials preliminary to thebeginmng of calcination and reserving it to a later stage, many of thedisadvantages of the ordinary operation are avoided and a number ofvnewa vantages gained. The preliminary finegrinding is anexpensiveoperation. Raw cement rock is usually a very hard material,

lng material not being good, so that it is.

requiring the expenditure of much power and the use of costly apparatusto reduce it to the usual flour-like fineness; and the same is true ofthe limestoneand of the slate employed in artificial mixtures, or insupplementing the natural mixtures. Clay is easier to grind than slatebut because of its greater volume as compared with slate, the latter isoften used. Furthermore, in this preliminary grinding an unduly largeamount of material must be handled since the raw material represents amuch greater weight than appears in the finished product. In calcinationnearly half of the calcium carbonate component (44 per cent.)disappears, being liberated as carbon dioxid which goes off with thestack gases, and'since the calcium carbonate forms about two-thirds ofthe totaLmixture, the diminution of weight in the kiln from thisreaction is large. There is also a diminution in weight due todehydration and drying. Countin all sources of loss of weight, it may besaid that it ordinarily requires about 600 pounds of raw material tomake a barrel of cement (380 pounds). It follows therefore that withoutconsidering the great hardness of much-or all the calcination iseffected, is

much greater than is due to the lessening in bulk and weight. Though theoriginal materials as stated, are often very hard and dense, after apreliminary calcination they etc., or direct mixtures of any kind ofcal-' careous materials w1th ar illaceous materlal,

are merely 'coarsely crus ed or broken andthen calcined as a travelingstream in a rotary cementvkiln apparatus by flame coming'from theclinkering flame. In "this, there is but little dusting and it is possible to get a much better "contact of the flame gaseswith the materialthan is ossi- .-ble with fine-powdered material forming a densethinstream with evolving gas permeating itsmas's and acting as ashielding are made minutely porous through the es- (gases 0mg.

layer. After the calcination is partially'or wholly effected, thematerial is removed from the kiln proper, sent through a fine grindingapparatus and returned to the kiln for clinkering, all in continuoustransit of such materials and with a continuous transit of flame andflame gases from the clinkering flame passing through such apparatus.

In the stated operation, I furthermore secure other economies in thehereinafter stated manner. Cal'cination, as previously stated, is veryinefficiently performed in the ordinary kilns and the utilization ofheat is not good, several times as much coal as is really necessarybeing used in making a barrel of cement. Waste gases are usually dischared at enormously high temperatures, usually well over 1500 F. One reasonfor this is the inefficient contact with the heat-L absorbing calciningmaterial usually secured in the upper part of the kiln, the gasespassing through the kiln being stratified. The hot gases from theclinkering flame ascend into the arch of the kiln and are underlaid by acooler stratum of the air brought into the mouth of the kiln by theinjector of the flame, by the entrainment action of such hot gases andby the great stack draft caused by the discharge of very hot wastegases. The velocity of the draft current prevents much admixture ofthese strata. With the underlying cooler stratum mixes the stream ofcomparatively cool carbon dioxid resulting from the calcination. I havediscovered that by admixing these strata, by procuring a, more positivecontact of hot gases with the material and by prolonging the time ofcontact, I can secure very much better results in calcination and inutilization of heat, discharging the waste ases at a temperature whichis very much lower than is usual; even as much as 1000 F. lower;discharging such gases at, say, about 400 to 500 F., or the temperaturenecessary to secure a good stack draft. The period of contact of hotgases J with the material undergoing calcination, I

have discovered, should be at least seven times as long as the time of exposure of the calcines to the direct action of the clinkering flame;and the ratio may be greater with advanta 7 e. Operating in this mannerand with fhe good utilization of heat stated, I am enabled to secureother desirable results, allowing me to pass the material to theclinkering 'zone in a completely calcined, comparatively hot conditionand without the usual sharp temperature differential at the boundingline of the clinker zone and without the production of rings, etc.

leave the clinkering On the other hand, the gases zone, where but littleif any absorption of heat occurs in this method of operation, with theirpractically full complement of heat'and produce a good andmethodicalDcalcining.

,VVith the gases, also, there is no sharp temperature differential atthe bounding line of rial into the c avay isto make the .kiln operatingin the described &

the clinkering zone and calcination consequently occurs in an even,regular manner, the per cent. of carbon dioxid in the calcining materialprogressively and regularly diminishing as such material travels forwardunder the influence of the regularly increasing temperature of the kilngases. With a deliver of completely calcined matelinkering zone and theconsequent abolition of the sharp temperature differential at itsbounding line, the whole operation of the kiln becomes much moreregular.

The desirable time-contact factor can be secured 'in a number ofways,.several of which I have disclosed in my copending application,Ser. No. 316,148, filed May 10, 1.906, wherein I claim broadly methodsand means for securing such time-contact factor. One such means 1s torearrange the condi-. tions in the kiln so that the clinkering flame andthe clinkering zone formed thereby shall occupy a less fraction of thetotal length of the kiln than is customary, such fraction not'exceedingan eighth of such total length, and being preferably even a lessfraction of such total length. Another kiln in sections with material orgases, or both, traveling at differen tv rates of speed through thesections wherein calcinat-ion and clinkering respectively occur.- Usingsuch a sevenfold timecontact, the calcination absorbs heat eflicient-lyfrom the ambient gases and the latter may be discharged at 400 F.orbelow. As the gas temperature in the clinkering zone is. in theneighborhood of 3000 F. the absorption of heat represents a greatshrinkage in the gas volume between the clinkering zone and the end ofthe kiln; perhaps four-fifths of the volume disappearing. And if thesamediameter of kiln be preserved throughout, this further means that inthe upper end of the kiln the speed of travel of the gases will bereduced materially and the time contact-factor reatly increased over thenominal sevenfoId figure above adopted. In a manner, the gaseswill betraveling swiftly in the clinkering zone where their volume is great ascompared with the sectional area of the conduit offered while in theupper end of the calcining zone they pass at a relatively slow speed,giving a good time-contact factor. The-cross-section of the chimney fluecan of course be made suitable to the new volume of' gases so as topreserve the proper draft through the kiln as a whole.

By using coarsely crushed material in lieu of fine-powdered in thecalcining zone and by using the preferred sevenfold time-contact factorwith its attendant slow travel of gases in such calcining zone, I gainthe enormous practical advantage of asubstantial freedom from dusting sothat ordinary comparatively low-temperature waste gases.

' construction 0 In this manner of operation the upper art of the kilnis its own dust collector, the ust picked up in the lower portion under.the

high speed ;of gas travel incident to the formation of a chnkeringtemperature being quietly dropped again as the heat of the gases isabsorbed and they cool andcontract and slacken in speed.

The regularity of operation of the kiln as a whole is also improved bythe use of coarsely crushed material in the calcining zone since it iseasier to obtain eflicient contact of the hot gases wit-h such coarsematerial than with a. stream of fine powder permeated by and bathed in abody of its own evolved gas. The coarse material gives a slow andregular evolution of as, which is swept away as fast as produce andtherefore the calcination is regular and progressive. Any residualcarbon ,dioxid remaining in the reground material is easily removed uponthe return of the fine-ground calcines to the kiln prior to their entryinto the clinkering zone.

In the securingiof goodcontact between the calcining material and thehot kiln gases, it is desirableto destroy Stratification in such gases.With the material in comparatively coarse-form and the good utilizationof heat secured, this may be done without undue dusting though in theordinary process bringi'n a current of very hot, swiftly moving flamegases, such as exists in the arch of the kiln, into immediate contactwith flour-like material would cause considerable dusting. By arran inthe kiln in a number of sections, pre era ly superimposed, connected bystationary housings good results are obtained: in the homogenizing ofthe kiln gases. With superimposed sections connected by stationaryhousing, the hot gas stratum or flame coming from the lower sectionstrikes the wall of this flue in a manner causing it to reverberate orrebound and tending to cause good admixture. Such a superimpositionwhere two sections are used has the further,

advantage of bringing the feed and delivery of the kiln on the sameside, facilitatingsupervision and reducing the cost of .labor. And sinceall the dust will be at thisend, the drive machinery can well bearranged at the other, giving an enormous practical advantage to such astructure as compared to other ways of ositioning the sections. This lthe kiln in sections connected by stationary housings is furtherconvenient 1n removing the calcined material for regrinding; and forthls ppr use the superimshown, more or less posed arrangement 1s alsoesirable.

In the accompanying illustration I-have iagrammatically, an

a vertical flue in a zone showing the elevation of clinker caused byrapid rotation.

The structure shown in Fig.

1 comprises munication, the lower section being provided with firingmeans and the upper communicating with waste gas removing means. The twosections may be of unequal length with the upper section the longer.There may be may be used, but two superimposed sections are desirableand convenient. With two sections connected as shown, the flow of thegases therethrough is reversed at the conadmixture. The sections may bedivided into subsections, each provided with its own drive means, wherethe total length of the kiln is considerable. The total length of thecommunicating kiln sections can be qu'te great with advantage, and ispreferab y much over a hundred feet to permit good and efiective contactof the kiln gases with the calcining material and thereby causeconcomitant utilization of heat and good calcination.

Withdrawal. of calcined material for the purpose of regrinding should bethrough a stationary housing connecting two kiln sections; and with thesuperimposed arrangegravity in their passage to the regrinding means.

Where marl and similar bulky materials are to be treated it is verydesirable to have part, at least, of the upper kiln section of increaseddiameter. After calcination the materials shrink considerably and takeup less room. With other and less bulky materials, such as dense cementrock or limestone or as cement rock or limestone mixtures, such anincreased diameter has the advantage of giving an increased holdingcatained in contact with the gases for the same longitudinal travel, andtherefore increasing the time contact factor. Width of kiln is in somedegreeinterchangeable with length in securing this time contact factor.And with the sectional kilns shown, since inclination and speedofrotation can be independently varied, a wide kiln section may be usedeither for the upper or the lower section. But I prefer the wider to be}the upper. Apart from its advantage with such bulky materials as themarl mixtures, and its adis a cross section of the kiln in theclinkering necting housing in a manner tending to ood ment shown the hotcalcines are assisted by pacity, enabling more material to bemainembodiment of my new apparatus as adapted I two superimposed kilnsections in. open commore than two sections and other connections eeaoesvantage in regard to gas velocity, it is better to have more space inthe upper kiln for the reason that the clinkering zone can handle more.material than the calcining zone in kilns of the same diameterthroughout. The coarsely crushed material occupies more space thanthefine-ground and for t is reason also it is desirable to have greatervolume'in the upper section.

Increased internal diameter in the upper kiln section may be obtained bylessening the thickness of lining or by widening the kiln sectionitself. The character of the lining of each section, may be made such aswill suit the character of the materialhandled therein.

In Fig. 1, 1 and 2'respectively designate the upper and lower kilnsections. The former is provided with a housing 3 at its upper end, withchimney stack 4 rising therefrom and a conduit 5 for raw material,

- containing screw conveyer 6, connected to 2 layer .or bulkier rawmaterial and also as bin '7. In the housing, chamber 6 is prolongeddownwardlyand sidewardly into a funnel shaped conduit 9 connected withconveying means, 10, the purpose of this structure being to remove anydust that may come from the kiln or the feed means. Door 11 gives accessto this chamber. The upper kiln section as here represented ,is aboutseven feet in diameter and has a thicker (not shown) of interior liningin its lower than in its upper portion, the heat in this lower portionbeing greater and the need for the heat insulation also greater, whileincreased capacity is useful in the 'upper portion, both foraccommodatin more s owing down gas velocities.-

At its lower end, the upper kiln section enters a stationary housing 12,containing a vertical shaft chamber 13, to which door 14 gives access.The upper end of the lower kiln section also enters this housing and thetion.

shaft chamber forms a flue carrying the hot flame gases from the lowersection to the upper. The floor 15 of the shaft chamber is given a sharpangle to guide such material as may fall upon it into the lower kilnsec- At the back pf the housing is a rear door 40 and a sloping chute 41extending to the end'of the upper kiln section and adapt ed to catchcalcined or partially calcined material delivered thereby and transmitit to recipient 42, whence conveyer 48 takes it to grinding mill 44.From the mill another chute 45, returns the regroundcaloines to thelower kiln section. I

The lower kiln section shown is generally like the upper. At its lowerend, it is inclosed by a hood 16 through which projects a coal or gasburner 17.. This may be arranged so as to throw the flame some distanceback, and for this purpose, if water jacketed, it may extend inward somedistance. Whatever the total length of the kiln, the firing means shouldbe arranged, as stated, to produce a clinkering zone of about one-eighththis length so that the material under treatment shall not be exposed toa clinkering temperature more than a seventh the time of its exposure toa calcining temperature. Coal may be fed to the burner 17 by the usualmechanism 18, the airnecessary to carry it being furnished by pipe 19.Drive means are shown at 20 and 21.

The clinker falling from the mouth of the lower kiln section descendsthrough shaft 22 down to and into the clinker cooler 23. This is also arotating cylinder set at an angle. At its lower end it is provided witha fan 24 introducing air through-pipe 25 ending in a bell mouth 26. Fromthe cooler the clinker is removed by the usual conveyer 27. It is ofcourse obvious that air sent into the said cooler is heated by theclinker and passing up the clinker shaft gains access to the kiln to aidin combustion. A portion of this 'hot air may be tapped into the fanfurnishing the air for the coal blast as by valved pipe 60. 7

So far as may be, access of air to the kiln is restricted to that comingin with the coal jetand that passing'in through the clinker cooler, andnot more than enough to furnish ready combustion of the fuel issupplied, such as may gain access through the usual sightin and etchingholes in the hood, bein allowed or in calculating the air supply fromthe two sources. 7

The clinker cooler is provided with door 31. The upper kiln section issupported through the floor by pillars 32, of iron or steel, surroundedby a thick coat of concrete.

The 0 eration of this sectional kiln is obvious. .he use of hot air inlimited quantities tends to obviate the Stratification incident toallowing unlimited access of cold air permitted inthe usual kilns. Suchunlimited access of cold air as a distinct stratum is further precludedby the' fact that the hot flame gases do not go to the stack as adistinct stratum carrying underlying air with it, the hot gases beingmixed and merged and made to till the barrel of the kilnin the calciningzone as well as being made to move slowly. Draft is rapid in thecalcining zone and in the stack but being slowed dpwn in theintermediate calcining zone cold alr is not sucked in in any greatamount. Shortlybeyond the end of the flame, the kiln gases-merge into amore or less homogeneous the kiln section 1, while the upper of hotgases 3 in kiln section 2 tends to flow into the lower art of kilnsection 1. structural ow tendency is opposed'to the natural tendency of1 hot. gases to overlie colder, the result is a very thorough mixture atthispoint. To aid in making the gas mass homogeneous, the lower kiln maybe rotated comparatively rapidly without fear of increasing dusting atthe waste gas exit, as would be'the case in integral kilns. Thisrotation may exceed one revolution per minute, and may even reach threerevolutions per minute, the usual feed being restored by lessening theinclination of the kiln section. The 'upper kiln section, to furtherincrease the mixing eflect, may have a reversed direction of rotation.

The rapidit of rotation ofthe lower section has the urther-advantagethat it carries the clinkering material up on the side ment. In thisview, 28 is the usual kiln lin-v ing and 29 is the clinker layer carriedup into the upperleft quadrant of the kiln by the ra id rotation.

In t e apparatus shown, the lower kiln section is set at a slightly lessangle than the upper and is adapted to rotate at a higher rate of speedto carry up the clinker layer.

The lower angle compensates for the increased speed in preservinguniform feed of material. The internal diameter of the kiln preferablythe uppermost section.

Theproduction of the stated'time-contact factor with an ap aratus of thenature of that herein descri ed is more specifically described and isclaimed in m divisional application, Ser. No. 494,698, led May 7, 1909.I

What I claim is 1. In a cement clinker burning apparatus,

means for calcining cement material in transit by flame gases, means forremoving and regrinding the calcined material after expulsion of carbondioxid therefrom and flame-heating means for clinkering the groundcalcines, said means furnishing flame gases for the calcining means, allin continuous transit.

2. In a cement clinker burning'apparatus, the combination with a rotarykiln having a section adapted for calcining and another andcommunicating section adapted for clinkering, of means for removing,regrindmg and As the increases from the lowermost to returning materialintermediate such sections and firing means common to and heating bothsuch sections.

3. In a cement clinker burning apparatus,

, therewith by a housing forming a connecting conduit for the continuouspassage of flame and flame gases from the'latter to the former, firingmeans for the clinkering secs tion furnishing hot gases for thecalcining and means for removing calcined materials from the calciningsection through said housing, regrinding and returning to the clinkeringsection. I

5. The process of producing cement clinker which consists in calciningthe raw cement forming materials in a rotary kiln to practicallycomplete expulsion ofCO grinding and mixing the same, and returnmg to arotary kiln, and reheating to form clinker, said calcining and reheatmgbeing performed by a common source of heat.

6. The process ofproducing cement clinker which consists-in calciningthe raw materials in a rotary kiln to secure expulsion of CO grindingand mixin the same and returning to a rotary kiln and reheating to formclinker, said calcining and reheating being performed by a common sourceof cat.

7. The process of producing cement clinker which consists in calcininraw materials in a coarsely ground con ition, fine grinding and mixingthe calcines, and reheating the powder to form clinker, said calciningand reheating being performed by a common source of heat. v

8. A continuous process of making Portland cement clinker consisting inpassing raw material throu h a primary rotary kiln, then pulverizingsald material, then passing said pulverized material through a secondaryrotary kiln, and during the passage of the material through said kilnspassing in continuous sucession through said kilns a volume of flame andflame gases, clinkering the pulverized material in the secondary kiln,and driving the carbon-dioxid from the raw material in the primary kiln.

9. The continuous process of making cement clinker which comprisespassing a stream of raw cement material through a primary calciningrotary kiln section,

9 gases being passed into the first named kiln through a regrindingapparatus and through for eflecting c a secondary rotary clinkering kilnsection, commmgled to alcination therein and being destroystratification thereinv and passing a current of hot flame and flame inpassing from the one kiln into the other.

gases through the several sections in contin- .uous transit, saidcurrent being reversed in ment clinker which comprises producing adirection at one point during its passage'to clinkering flame in the lowinclined rotary kiln apparatus, said flame be- 10. The continuousprocess of making ce ing adapted to create .clinkering conditionsyingmore than one- ,of said apparatus, 50

produce a co'mmingling of strata therein.

' -1nent clinker which comprises passing hot in a 10 flame gases over -atraveling stream of ing said flame gases.

ment clinker which comprises producing a the flame and flame gases.

' 14. The continuous process 0 r which comprises ret from a clinkeringflame in cona traveling stream of coarsely al until said gases intemperature (1 said material passing the cale-grindi'ng ap d-material inproximity to a d hot gases, of said hot gases being ment clinker whichcomprises calcining a homogenized to remove stratification priortraveling stream of'coarsely crushed cement to contacting with materialin a rotary kiln-having a, current of material. I

- In testimony where flame of temperature suflicient to induceclinkering in its immediate proximity, passvment clinke ing hot flamegases therefrom over a stream .flame gases of coarsely crushed cementmaterial to protact with duce a calcination therein, regrinding thecrushed cement materi material so treated and passing the reground haveacquired the minimu necessaryfor stack draft an flame and the flamegases coming therefrom, has undergone a calcination said material beingexposed to the eflect of cined material through a said flamegases for aperiod at least seven paratus and passing the times as long as it isexposed to the direct as a traveling stream clinkering flame fu 12. Thecontinuous process of making cethe flowing current 2 material as astream in proximity -to said influence of said flame.

flame gases passing therethrough in o posite cines and-returning to arotary kiln for further treatment by a clinkering flame and the hotflame gases therefrom, said flame 13. The continuous process of makingcezone not occup eighth the total length coarsely crushed cementmaterials to calcinepassing .coarsely crushed cement material, the same,regrinding the calcined materials through an upper part of said kilnappaand passing the reground material as a travratus in cont elingstream in proximity to a clinkering from said flame unti 15 flame toproduce clinker, said'flame furnish-. removing the treated materials andregrindurning the reground ma-' ing the same ,andret 11. The continuousprocessof making ceterial to the kiln for further treatment by FLETCHERP. SCOFIELD.

fine groun rnishi'ng sai er portion of an act with flame gases coming 1a calcination is eifected,

f making ceaining hot said coarsely crushed of, I aflix signaturedirection, removlng' and regrinding t e calin the presence oft-W0witnesses.

GARLETON ELLIS.

